The call for restraint came as Sergei Lavrov, Russia’s foreign minister, was expected to meet his Iranian counterpart in New York to discuss Iran’s secret uranium enrichment plant.

There remain few signs, however, that Russia is ready to get really tough with Iran, a close trading and political partner. Russian analysts say Moscow would need cast-iron proof that Tehran is developing nuclear weapons before it would sign up to new sanctions. Most of Moscow’s pronouncements appear designed to delay any move to slap Tehran with sanctions for as long as possible.